vSlider Edit Plugin Warning Increase Image Capacity

Hello Friends,

Is it possible, or (un-wise) to edit a plug-in?
I am using the vSlider 4.1.1 and am very happy with it.

Site location:
http://naturallygiftedbaskets.com/wordpress/

Unfortunately, I can only load 20 images. I have nearly 30 to load.
I have looked at:
>Plugins >Edit >vSlider >Edit Plugins >Editing vslider/vslider.php (active)

But on this page there is a line of text:
“Warning: Making changes to active plugins is not recommended. If your changes cause a fatal error, the plugin will be automatically deactivated.”

Question if I make a change to the code on this page am I running the risk of losing my vSlider?

Question 2: Not even sure if this is the page I would adjust for image amount increase. I found the following:

<p><?php _e(“Slides”, ‘vslider’); ?>:
<select name=”<?php echo $option; ?>[slideNr]”>
<?php for($s=1; $s<21; $s++){ ?>
<option value=”<?php echo $s; ?>” <?php selected($s, $options[‘slideNr’]); ?>><?php echo $s; ?></option>
<?php } ?>

I was going to change:

($s=1; $s<21; $s++){ ?>

to

($s=1; $s<31; $s++){ ?>

However not even sure this would give me the 30 images instead of only 20 or not?

Any insigght to either or both my questions would be very much appreciated. Many thanks in advance for your time and assistance.i